This invention relates to a printing machine in general and more particularly to a printer of a wire-dot impact type.
There have been proposed a printer of a type wherein a printing paper is passed between a printing head and a platen having a plurality of sintered members saturated with different color inks mounted on the periphery thereof, and the paper is pressed against a selective one of the ink saturated members by means of wires in the printing head, so that a color print may be effected. According to the prior art, an electric motor or the like has been employed for rotating the platen to thereby select a desired one of colors to be printed on the paper, in addition to two motors for transporting the printing head and the paper, respectively, resulting in increase in the size of the printer as well as in complexity of the individual drive motors.
Moreover, when a relative position is changed between the platen and the printing paper, the paper may touch the platen and thus be contaminated by the ink saturated members of the platen, especially when the paper is displaced relative to the platen, because the paper will be often slackened or skipped while being transported with respect to the platen. In this connection it is to be noted that the platen is caused to rotate for color changing operation, but at this time the paper is stopped from running while the platen is simply rotated around a predetermined center axis. Therefore there is little probability of the paper being contaminated by ink. Thus, the paper contamination will become serious at the time of feeding paper, especially at the time of changing the line to be printed.